The semiconductor technology node becomes smaller and smaller following the development tendency of Moore's law, with the continuous development of the semiconductor technology. Accordingly, the channel length of a metal-oxide-semiconductor field-effect transistor (MOSFET) has to decrease. This provides advantages of increasing density of the semiconductor elements and the switching speed of the MOSFET.
However, the distance between the source and drain electrodes of a device also decreases, as the channel length decreases. Correspondingly, the controlling ability of the gate structure over the channel becomes worse, and it also becomes harder for the gate voltage to pinch off the channel. As a result, sub-threshold leakage, also known as short-channel effects (SCE), may easily occur.
To better adapt to the decreased size of the devices, focuses of the semiconductor technology have gradually changed from planar MOSFETs to more effective non-planar three-dimensional transistors, such as fin field effect transistors (FinFETs). In a FinFET, the gate structure can control an ultra-thin part (fin) from two sides of the fin, to provide a much stronger controlling ability on the channel and to effectively suppress the short-channel effect. Moreover, compared with other devices, FinFET is more compatible with the present fabrication processes for integrated circuits.
However, performance of conventionally fabricated FinFET devices still needs to be improved. The disclosed devices and methods are directed to at least partially alleviate one or more problems set forth above and to solve other problems in the art.